Patent Document 1 discloses that, in a compressor in which rotation of a swash plate fixed to a drive shaft is converted into reciprocating motion of a piston via a shoe, a surface covering layer mainly of tin having self-lubricating properties is formed on a fitting part of the piston in sliding contact with the shoe. In the compressor disclosed in Patent Document 1, the effects of the surface covering layer mainly of tin can reduce frictional resistance between the piston and the shoe, and can prevent seizing at sliding portions between the piston and the shoe associated with the lack of lubrication.